As a belt retracting device (belt retractor) to retract a seat belt used to safely keep a vehicle occupant or a like on a seat, conventionally, an emergency locking-type retractor equipped with an emergency locking-mechanism to automatically lock the retractor by using an inertia detecting means that acts to rapid acceleration, collision or rapid deceleration is used (For example, Japanese Patent Application Laid-open No. Sho 50-79024, Japanese Patent Publication No. Sho 59-21624, and Japanese Utility Model Publication No. Hei 02-45088).
The conventional belt retractor is controlled in a manner in which, for example, when collision is judged as unavoidable, a seat belt (webbing) is reeled by using a motor to raise tension of the seat belt and, after the tension reaches a predetermined level, the tension of the seat belt is lowered.
By controlling as above, for example, even when the judgement that the collision would be unavoidable was not correct and the collision did not occur actually, needless restraining can be avoided and no unpleasant feeling is given to a vehicle occupant.
However, if the belt retractor is so controlled that the tension of the seat belt is lowered immediately after the tension has reached a predetermined level following the rise of the tension of the seat belt, the seat belt is locked for drawing before the tension is restored to its original level reached before the rise in the tension. This is because, when the seat belt is drawn out, the locking mechanism is still kept in a lockable state in which the drawing of a seat-belt is inhibited (for example, in a state in which a condition is being met under which the drawing of seat-belt to be performed when a speed of a vehicle is decelerated at a level exceeding a predetermined one; for example, due to a driver's rapid operation of a brake is locked). Here, there is a problem in that, in such a case as above, it is necessary that the seat belt is reeled again to release the locking of drawing, thus causing a vehicle occupant to be further restrained which gives an unpleasant feeling to a vehicle occupant.
To solve this problem, technology is disclosed in, for example, Japanese Patent Application Laid-open No. Hei 11-198760) in which a belt retractor is controlled in a manner in which, when the collision is judged as unavoidable, a seat belt is reeled to raise a tension of the seat belt and, after the tension of the seat belt reaches a predetermined level, the reeling operations are continued for a predetermined reeling-continuing time (for example, 5 seconds) and, at the best time when the condition for locking the drawing is judged to be not met, the tension of the seat belt is lowered.
However, according to the above conventional technology, in the above reeling-continued time is included time during which the condition for locking of drawing is being met (that is, time during which the locking mechanism is in a lockable state) and, therefore, it is necessary that the reeling continuing time is set to be longer than the time during which the above condition is met.
Additionally, since the time during which the condition for locking of drawing varies depending upon a way of pressing a brake pedal, a speed of a vehicle reached before an operator's rapid operation of a brake, and a way of action of an inertial force to be exerted on a vehicle when collision is avoided by the rapid operation of the brake, in order to avoid an unpleasant feeling that may be given to a vehicle occupant due to a repeated rise in the tension of the seat belt required for releasing the locking described above, it is necessary that the above reeling-continuing time is set to be as long as possible.
As a result, the conventional belt retractor has a problem in that, even when a judgement that collision is unavoidable was not correct and the collision did not occur, a vehicle occupant must endure a pain with being restrained on a seat during a period of the fixed and comparatively long time.
In view of the above, it is an object of the present invention to provide a restraining and protecting apparatus for a vehicle occupant which is capable of avoiding needless and long-time restraining of the vehicle occupant by a seat belt and of not giving an unpleasant feeling to the vehicle occupant.